1. Field of the Invention
This invention relates to a means and method of moving and transferring a stack of lumber or the like from a row of stacks wherein the the stacks are arranged close together in a side-by-side relationship.
2. Description of the Prior Art
In a sawmill or lumber yard environment, sawn lumber units move sidewise on a so-called "green line" to a stacking area where they are manually removed one by one from the line, inspected as to size and the like, and stacked by size and the like to form a row of closely spaced, side-by-side stacks adjacent the line. When a sufficient quantity of a particular size lumber has been accumulated in a stack, that stack must be quickly removed from the line and stacking area, and transported to a storage location within the yard. In the past these stacks of sorted lumber were moved away from the line and other adjacent stacks by means of carts or straddle trucks.
With the use of carts, typically multi-wheeled low profile vehicles, the lumber which has been sorted was stacked directly upon a wheeled cart. When a sufficient quantity of lumber had been stacked, the cart was pulled from the line to a storage location within the lumber yard, and a second cart was inserted in its place within the stacking area adjacent the line. This method of moving and transferring a stack of lumber necessitated the use of a multiplicity of carts to accommodate the numerous stacks of sorted lumber adjacent the line and those stored at locations within the yard.
With the use of straddle trucks, adjacent stacks of sorted lumber had to be spaced far apart to enable the truck to maneuver around and above the stack to be removed. Since these stacks are sorted and stacked manually, the increased distance between adjacent stacks increased the stacking time. When a sufficient quantity of sorted lumber had been accumulated in a stack, the straddle truck removed the stack from the line and delivered it to storage within the yard. This meant the truck had to leave the vicinity of the stacking area further increasing the stacking time. Finally, straddle trucks per se are expensive and complicated pieces of equipment and are subject to the relatively complicated maintenance problems associated with such equipment.
As will be discussed more fully, the means and method of moving and transferring a stack of lumber according to the present invention overcomes these limitations of prior stack moving practice. The present invention provides a transfer unit comprising an essentially rigid rectangular frame slightly wider than a stack of sorted lumber and roller supported at one end. The frame is progressively moved by forklift truck under a selected stack such that the weight of the stack is eventually supported by the frame. The frame and stack may then be withdrawn from the line where the forklift truck can remove the stack from the frame and transport it to a storage location within the yard. The same frame may then be repositioned under another selected stack and the process repeated.